Blood tests are a common part of routine treatment and preventive care. A doctor will often prescribe a blood test before or after a medical checkup. A doctor may also prescribe blood tests to determine particular conditions.
This article looks at some of the most popular blood test forms, and what what test looks for.
During a routine physical, a doctor may order one of the following tests:
Complete blood count
A complete blood count (CBC) measures a variety of the blood’s components, such as:
- red blood cells
- white blood cells
- mean corpuscular volume (MCV) — the average size of a person’s red blood cells
- hematocrit — how much space red blood cells take up in the blood
A CBC examination helps a doctor diagnose illnesses or blood disorders, such as anemia, clotting issues, inflammation, infection, or immune system disorders. Before a CBC exam, a person will only need to fast if their doctor asks them to.
Blood enzyme tests
Blood enzyme tests measure serious enzyme levels within the body. The body produces enzymes which help control the body’s chemical reactions.
Blood enzyme tests may help a doctor identify specific health issues, including a heart attack. If a doctor suspects a heart attack, the levels of the cardiac troponin enzyme that the heart releases when it is injured are checked.
Blood clotting tests
A blood clotting test, also known as a coagulation panel, is searching for a protein that will help clot the blood. A doctor can order the test if the person is suspected of having a blood clotting disorder.
If a person takes warfarin or other blood thinning drugs, a doctor will probably use a specific test for blood clotting as part of routine monitoring.
If a doctor wants to determine a person’s risk of developing coronary heart disease or other atherosclerotic complications, a lipoprotein, or lipid, panel would possibly be requested. A panel of lipoproteins will provide information concerning a person’s:
- low-density lipoprotein (LDL) cholesterol level
- high-density lipoprotein (HDL) cholesterol level
- total cholesterol level
- triglycerides level in the blood
A person will have to fast for 8 to 12 hours before a lipoprotein panel, according to the Department of Health and Human Services.
If the results indicate elevated levels of any cholesterol or triglycerides, the person may be at increased risk of developing cardiovascular disease.
Basic metabolic panel
The basic metabolic panel (BMP) measures the levels of the various chemical substances present in the blood plasma portion.
The BMP, also known as a blood chemistry 8 test, provides bone, muscle, and organs information.
A doctor will tell an patient whether, and for how long, they need to fast before a BMP check.
The following BMP tests look at:
- Uncorrected calcium levels: Abnormal calcium levels could indicate a person has an underlying condition related to their kidneys or bones, cancer, malnutrition, or other diseases.
- Glucose level: Higher than normal blood glucose levels could indicate a person has diabetes or is at risk of developing diabetes. Some people may need to fast before a blood glucose test.
- Kidneys: The presence of excess waste products in the blood, such as blood urea nitrogen (BUN) and creatinine, can indicate a problem with the kidneys.
- Electrolytes: The presence of abnormal electrolyte levels could indicate an issue with dehydration, kidneys, or other underlying conditions.
Why do some tests require fasting?
What a person eats affects the blood level of the specific components. For example, the level of blood sugar in an individual, specifically the amount of glucose, should temporarily increase after eating.
A person typically must not eat a blood sugar check for several hours.
Other tests, such as a fasting lipid panel, also require quicking. A individual will check with their physician to see if they need to fast before a test.
Who should get routine blood tests?
A person should talk to their doctor about the routine tests that they need. A doctor can order a blood test only if they have questions about other illnesses, or as part of a preventive health plan, they can qualify for an annual check.
People taking other drugs for thinning the blood may need regular blood tests. A doctor will advise them on the length of the tests depending on their risk factors and needs.
People may get a blood test at the doctor’s office. Many tests, however, may require the person to go to a specialist hospital or centre.
How long do results take?
Result times will differ depending on the type of test the individual has had. The waiting time for some examinations is a couple of minutes. The waiting time for other exams is a couple of days or more.
A person should ask their doctor how long it could take for the results to return. They should also confirm whether the doctor will receive the results, or whether the laboratory will directly send them to the patient.
What to expect
A blood test typically involves a health care provider inserting a needle into the person’s vein to draw blood, generally an arm.
A health care provider will often tie a rubber band around the arm to more easily see the veins in the arm and disinfect the region with an alcohol swab before inserting the needle.
The person may feel a pinch as the needle reaches the vein, which lasts just a second or two.
Obtaining a blood test sample will typically last no more than 3 minutes.
After a blood draw a person can feel faint. Anyone who feels lightheaded will stay sitting until the feeling passes.
Are there any risks?
Doctors and health care providers typically see blood tests as healthy at the blood test site, with limited risk of infection.
Someone showing injection site signs of infection, such as inflammation, swelling, redness and fever, should call their doctor.
Severe bleeding can occur rarely. People who take blood thinners, or who have other underlying conditions that cause excessive bleeding, are more likely to experience this.
People may discuss with their doctor any potential concerns about side effects before having a blood test.
Usually, blood tests are a part of routine preventive care. A doctor sometimes recommends blood tests as part of a physical or if they believe a person may have a condition behind it.
The blood tests are with little to no risk in and out of procedures. A person should talk to their doctor about fasting before their test, and when they can expect to receive the results.